China Eastern Airlines, one of the mainland's top three air carriers, has admitted for the first time that 'human factors' were behind disruptions to more than 20 flights from Yunnan province a week ago.

'Among the 21 flights that returned [without landing at destinations on] March 31 and April 1, some were not a result of bad weather, as the crew claimed, but some apparent human factors,' Xinhua reported yesterday, quoting a China Eastern Airlines statement.

Two top officials from the carrier's Yunnan operations, one of them general manager Yang Xu, were suspended over the incidents.

They highlighted simmering tension in the industry between the airline's management and pilots over benefits and working conditions. Disputes have grown as rapid development in the airline industry over the past 10 years has overextended resources, including trained pilots.

Pilots working for state-owned airlines earn between 30,000 yuan (HK$33,359) and 40,000 yuan a month, much less than those working for private carriers. They regularly complain about worsening conditions and say they are forced to work longer hours or shorten their holidays to meet demand.

Mainland carriers have also imposed hefty fines of up to 10 million yuan on pilots for breaking contracts, making it virtually impossible for pilots to change airlines for better pay. Pilots at China Eastern Airlines' Yunnan branch were particularly dismayed when the provincial government, seeking ownership of the Yunnan arm of the airline, cancelled a tax break they enjoyed after China Eastern had rejected its acquisition offer.

For days, China Eastern had maintained that the disruption of outbound flights from Kunming , Yunnan's capital, was the result of bad weather and that it was up to pilots to decide whether conditions were good enough to fly.

Weather forecasters and industry analysts dismissed the claims, setting off a strong public outcry over the pilots' behaviour.

Under mounting pressure, the mainland's air traffic watchdog, the Civil Aviation Administration of China, launched an investigation and said it would slap lifetime bans on the pilots involved.

China Eastern said yesterday that the pilots were temporarily grounded pending further investigation, and it apologised for the inconvenience to travellers and the bad publicity.

The company said it had compensated some passengers and would continue to do so in accordance with industry regulations.

But the compensation is unlikely to assuage anger among the 1,000 stranded passengers. According to mainland media, more than 30 are considering a class action lawsuit against the airline for what they described as 'commercial deception'.